TDM (T1/E1) Info & Statistics

Key points about the GigaPlus TDM

Clock Source

The T1/E1 clock source used by the IDU to send frames over the air comes from the connected equipment – The GigaPlus will use this timing and synchronize the far end T1 TX clock to it.

Framing

The framing structure used for the E1 and T1 connection is Extended Superframe (ESF). All data input must utilize this format. E1 uses HDB3 Line Coding

Output Level

The GigaPlus shapes the pulses of the T1 output to support a line buildout of 0 to 120 feet using 100 Ohm twisted pair for T1 or 120 Ohm twisted pair for E1 circuits.. Output voltage is +/- 3 Volts nominal.

Loss-of-Signal (LOS) Alarm

Detects a loss of input T1/E1 signal  or low input signal level on the local  IDU front panel of the unit.  The IDU will inject RAI and AIS signals to the other end of the link while the LOS is in alarmed state. The loss-of-signal (LOS) alarm is raised when the input T1 or E1  level drops below the threshold at which a bit error rate (BER) of 1 in 103 is predicted. This can be the result of excessive attenuation of the signal, receiver saturation, cable cut, or equipment fault. The LOS state clears when two consecutive framing patterns are received and no new LOS condition is detected.

Loss-of-Frame (LOF) Alignment

The LOF state occurs when incoming frame on the local IDU T1/E1 front panel signal is out of alignment.  This can occur if the framing structure is incorrect of if the clock source is not accurate. The IDU will inject RAI and AIS signals to the other end of the link while the LOS is in alarmed state.

Alarm Indication Signal (AIS) Blue Alarm

Indicates that unframed signal is present on the local IDU front panel input.

Remote Alarm Indication (RAI) Yellow Alarm

This indicator, displayed on the local radio IDU, is received from the far end of the radio link when the remote radio loses its incoming TDM signal.  The far end signal input must be checked.

CRC-N (CRC) Block Counter

Cumulative block error counter from the local IDU front panel input. CRC-4 is used for E1 and CRC-6 for T1.

Excessive-CRC (Ex-CRC) Counter

More than 15 consecutive CRC errors on the local IDU front panel input.

Far End Block Errors (FEBE) Counter

Integer indicating block errors from the far end IDU.

Line Code Violations (LCV) Counter

Indicates the line coding on the local IDU front panel input is not correct or does not meet the mask. Line code must be B8ZS.  If the cable length is too long or not constructed properly the waveform may not meet the mask or be distorted, which can result in LCV errors.